The present invention relates generally to therapeutic radioactive implants and methods of use thereof, and more particularly to radioactive devices for implantation into a cavity of a patient""s body and methods of use thereof.
Gross surgical removal of tumorous tissue can leave behind traces of tumorous, precancerous, or other diseased tissue which can foster recurrence or metastasis of the tumor. Accordingly, the site of removal of a tumor is often treated postoperatively in an attempt to destroy any such diseased tissue left behind by the surgery. Conventional techniques for treating the site of surgical removal of a tumor include post-operative administration of radiation, chemotherapy, and/or heat.
Currently, external beam therapy and short-range therapy are two commonly practiced techniques for administration of post-operative radiation. In external beam therapy, also known as teletherapy, an external radiation beam is directed at the treatment site. In teletherapy, the radiation beam must be carefully positioned with respect to the treatment site to minimize the radiation exposure of the surrounding healthy tissue. Even with a high degree of precision, however, healthy tissue in the vicinity of the treatment site may receive significant doses of radiation. This side effect can be compounded when treatment requires repeated administrations, each requiring careful positioning of the radiation beam.
In short-range therapy, also known as brachytherapy, radioactive sources are placed at or near the treatment site to provide site-specific delivery of radiation therapy, potentially reducing undesirable side effects associated with teletherapy, such as irradiation of healthy tissue. A common brachytherapy technique uses catheters to deliver radiation to the treatment site. In this technique, numerous catheters may be simultaneously inserted into the treatment site, sewn into place, loaded with solid isotopic pellets for a prescribed time, and then removed. The process of placing a number of catheters simultaneously within the appropriate region is cumbersome and time-intensive. Additionally, invasive insertion and external exposure of the catheters presents an increased risk of infection to the patient, and can result in significant discomfort for the patient during treatment. Finally, any subsequent treatment, for example, treatment following tumor recurrence, requires that the entire process be repeated from the beginning.
Another common brachytherapy technique employs radioactive implants to deliver radiation therapy. In this technique, numerous radioactive pellets or seeds are implanted directly into the treatment site. Several varieties of radioactive seeds are currently available, including cylinders that contain radioactive sources and bodies that include radioactive layers. However, the radiation fields generated by the implants are typically highly non-uniform, resulting in highly non-uniform distributions of radiation dose across the treatment site. Also, the seeds are not typically implanted in the cavity formerly occupied by the bulk of the tumor at the time of excision, thus generally requiring further surgical incisions. Lastly, the seeds are typically made of materials that do not conform to the outline of the cavity to be treated, thereby reducing the therapeutic efficiency of the implants.
A device for providing radiation treatment to a treatment site that can be implanted at the time of tumor removal and which delivers a more uniform dose of radiation throughout the surrounding tissue would be desirable.
In accordance with one embodiment, the present invention is directed to a device for the administration of radiation to tissue adjacent a cavity wall. The device includes an outer portion that has a size sufficient for implantation adjacent the cavity wall of a cavity, e.g., of a size sufficient to substantially fill the volume of the cavity. The outer portion may be made of a biocompatible material having low radiation absorption, to facilitate transmission of radiation to the tissue adjacent the cavity wall. The outer portion may be made of an elastic biocompatible material, so that the outer portion conforms to a contour of the cavity wall to provide close approximation to the tissue therealong. The device further includes at least one radioactive source. The radioactive source may be encapsulated by the outer portion, e.g., positioned in an area spatially located from a periphery of the outer portion. A radioactive source may be a radioactive nuclide that decays by electron capture, without the emission of beta particles. Such a radioactive nuclide may decay with the emission of X-rays, for example, having a weighted average energy from about 20 keV to about 100 keV. The radioactive nuclide may be selected from palladium-103, iodine-125, gadolinium-153, samarium-145, and ytterbium-169.
In accordance with another embodiment, the present invention includes a method for the treatment of tissue adjacent a cavity wall. Such a method may include identifying a cavity within a body of tissue, e.g., by removing a portion of tumorous tissue within a body of tissue so as to generate a cavity. The method also includes placing within the cavity a device, such as described above, having an outer portion and at least one radioactive source, e.g., in which the outer portion has a size sufficient for implantation adjacent the cavity wall, and the radioactive source is positioned within an area spatially located from a periphery of the outer portion for delivering radiation therapy to the tissue adjacent the cavity wall.
The present invention also provides methods for manufacturing devices, such as described above, useful in the methods disclosed herein.
Further features and advantages of the present invention will become apparent from the following description of embodiments and from the claims.